Ballast cleaning machine

ABSTRACT

A ballast cleaning machine comprises a machine frame comprising two frame parts, one of the ends of one machine frame part adjoining one of the ends of the other machine frame part while the machine frame part ends opposite to the one ends are remote from each other, and the adjoining machine frame part ends being pivotally linked to each other for pivoting about a vertical axis. Respective undercarriages support the machine frame on the track, two of the undercarriages being arranged at the remote machine part ends and a third one of the undercarriages being arranged on one of the machine frame parts in the range of the vertical pivoting axis. An endless ballast excavating chain is arranged on a first machine frame part, the chain including a transverse section extending for operation under the track, a ballast screening arrangement is arranged to receive excavated ballast from the chain, and a track lifting device is arranged on the first machine frame part adjacent the transverse ballast excavating chain section. A drive connects the third undercarriage to the one machine frame part whereon it is arranged for longitudinally displacing the third undercarriage whereby the spacing between the third undercarriage and the track lifting device may be varied.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a ballast cleaning machine forexcavating ballast from underneath a track and for receiving, cleaningand transporting the excavated ballast, which comprises a machine framecomprising two frame parts, each machine frame part having oppositeends, one of the ends of one machine frame part adjoining one of theends of the other machine frame part while the machine frame part endsopposite to the one ends are remote from each other, and the adjoiningmachine frame part ends being pivotally linked to each other forpivoting about a vertical axis. Respective undercarriages support themachine frame on the track, two of the undercarriages being arranged atthe remote machine part ends and a third one of the undercarriages beingarranged on one of the machine frame parts in the range of the verticalpivoting axis. An endless ballast excavating chain is arranged on afirst one of the machine frame parts, the chain including a transversesection extending for operation under the track, a ballast screeningarrangement is arranged to receive excavated ballast from the chain, anda track lifting device is arranged on the first machine frame partadjacent the transverse ballast excavating chain section.

(2) Description of the Prior Art

U.S. Pat. No. 4,538,686, dated Sept. 3, 1985, discloses a self-propelledballast cleaning machine which comprises a machine frame whose oppositeends are supported by undercarriages on the track. Arranged between themachine frame ends are an endless ballast excavating chain including atransverse section for operation under the preferably lifted track, atrack lifting device and a ballast screening arrangement arranged toreceive the excavated ballast from the chain. The track lifting strokeis limited by the two undercarriages at the opposite ends of the machineframe so that it may not be possible to lift the track sufficiently foraccommodating the transverse chain section therebelow in track sectionswhich have a relatively shallow ballast bed. On the other hand, a longerwheel base, which would enable the track lifting stroke between theundercarriages to be correspondingly increased, causes the endlessballast excavating chain to extend in track curves laterally beyond thetrack during movement of the machine between operating sites.

U.S. Pat. No. 4,538,687, dated Sept. 3, 1985, discloses a ballastcleaning machine comprising a tripartite machine frame, the adjoiningends of the machine frame parts being pivotally linked to each other forpivoting about vertical axes. The machine frame of this high-efficiencymachine is supported on the track by undercarriages arranged at theremote ends of the two outer machine frame parts as well as in the rangeof the pivotal links of the outer machine frame parts with theintermediate machine frame part. The intermediate, bridge-like machineframe part carries an endless ballast excavating chain including atransverse section for operation under the preferably lifted track, atrack lifting device and a high-capacity ballast screening arrangementarranged to receive the excavated ballast from the chain. A retractibleauxiliary undercarriage is mounted on the intermediate machine framepart ahead of the ballast excavating chain in the operating direction ofthe machine for use only during movement of the machine betweenoperating sites. A vertical adjustment drive for this retractibleundercarriage is arranged in the range of the pivotal link between theintermediate and leading machine frame parts to enable the front end ofthe intermediate machine frame part with this undercarriage to bevertically adjusted with respect to the leading machine frame part andthe track. In this way, the distance between the two undercarriageswherebetween the track lifting device is arranged may be increasedduring operation of the machine to insure sufficient lifting of thetrack. On the other hand, lowering of the retractible undercarriage intoengagement with the track enables the machine frame to be properlysupported on the track so that the machine may be incorporated into atrain for movement between operating sites while assuring that theexcavating chain will not unduly extend laterally beyond the track insharp track curves. To enable the transverse ballast excavating chainsection, which has a considerable height to increase its excavatingcapacity, to be inserted under the track even if the ballast bed is tooshallow to permit a normal lift of the track, a continuously operatingballast tamping arrangement is mounted on the leading machine frame partto increase the height of the bed. This lifting of the track ties bytamping ballast under them ahead of the ballast excavation has been verysuccessfully used in commercial track rehabilitation but requires theadditional tamping stage. An increased lifting stroke can be effected bythe track lifting device only if the undercarriages were spaced fartherapart but this would cause the transverse chain section to extend undulybeyond the track in sharp curves.

U.S. Pat. No. 3,690,262, dated Sept. 12, 1972, relates to a trackrehabilitation technology fundamentally different from ballast cleaning,i.e. it discloses a track correction and tamping machine with anelongated machine frame supported on undercarriages, the wheel base ofthe machine being extensible for improving the track lift during tampingand track repositioning. For this purpose, the tamping and track liftingunit is mounted between a rear and intermediate undercarriage, anadditional front undercarriage being longitudinally and verticallyadjustably mounted at a front end of the machine frame. During operationof the tamper, this front undercarriage is longitudinally displaced intoa forward position and lowered into engagement with the track, while theintermediate undercarriage is lifted out of engagement with the track sothat the track is freely movable at this point. This structure increasesthe track lifting stroke of the tamper lifting unit and enablesadditional ballast to be tamped under the ties.

SUMMARY OF THE INVENTION

It is the object of this invention to improve a ballast cleaning machineof the first-described type so that the track may be lifted higherbetween relatively widely spaced undercarriages whereby the insertion ofthe transverse ballast excavating chain section under the track isfacilitated while, at the same time, the endless ballast excavatingchain and, more particularly, its transverse section, will remain withinthe lateral boundaries of the track, even in sharp track curves.

The above and other objects are accomplished in such a machine accordingto the invention with a drive connecting the third undercarriage to theone machine frame part whereon it is arranged for longitudinallydisplacing the third undercarriage whereby the spacing between the thirdundercarriage and the track lifting device may be varied.

Such a ballast cleaning machine with a longitudinally displaceableundercarriage is structurally very simple since the machine frame partscarrying very heavy loads as well as the pivotal links connecting theseframe parts are in no way affected by the structure which enables thewheel base to be varied. The longitudinal displacement of the thirdundercarriage enables the ballast cleaning machine to be simply andrapidly adapted to the prevailing operating conditions to change thetrack lifting stroke without interfering with the ballast cleaningoperation. For moving the machine between operating sites, the thirdundercarriage may be rapidly displaced by remote control of its driveinto an end position closest to the track lifting device. This preventslaterally projecting portions, particularly the ballast excavatingchain, from extending laterally beyond the lateral boundaries of thetrack and also complies with official regulations regarding maximalwheel bases for railroad cars.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, advantages and features of the presentinvention will become more apparent from the following detaileddescription of a now preferred embodiment thereof, taken in conjunctionwith the accompanying, somewhat schematic drawing wherein

FIG. 1 is a partial side elevational view of a ballast cleaning machinewith a longitudinally displaceable undercarriage,

FIG. 2 is a top view of the ballast cleaning machine of FIG. 1,

FIG. 3 is an enlarged fragmentary top view of a portion of the machineincorporating the longitudinally displaceable undercarriage, and

FIG. 4 is a cross section along line IV--IV of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawing, there is shown ballast cleaning machine 1for excavating ballast from underneath a track comprised of rails 10fastened to tie 11 and for receiving, cleaning and transporting theexcavated ballast. The machine comprises elongated machine frame 5comprising first frame part 2 intermediate one leading frame part 3 andanother rear frame part 4, as seen in the operating direction of machine1 indicated by arrow 26. Each machine frame part has opposite ends andone of the ends of one machine frame part adjoins one of the ends of anadjacent one of the machine frame parts while the machine frame partends opposite to the one ends are remote from each other. The adjoiningends of machine frame parts 2 and 3 are pivotally linked to each otherat pivotal link 7 for pivoting about vertical axis 6 which the adjoiningends of machine frame parts 2 and 4 are pivotally linked to each otherat pivotal link 8 for pivoting about a vertical axis. Respectiveundercarriages support machine frame 5 on the track, two of theundercarriages being arranged at the remote machine part ends and athird undercarriage being arranged on one of the machine frame parts inthe range of the vertical pivotal axis.

As shown, an undercarriage constituted by four-axle swivel truck 9supports the rear end of intermediate machine frame part 2, which islinked to rear machine frame part 4, on the track while undercarriage 39supports a front end of leading machine frame part 3 on the track. Thirdundercarriage 12 is arranged on machine frame part 3 in the range ofvertical pivoting axis 6 and hydraulic drive 14 connects the thirdundercarriage to machine frame part 3 for longitudinally displacing thethird undercarriage in the direction of track elongation. Endlessballast excavating chain 18 is arranged on first machine frame part 2and includes transverse section 36 extending for operation under thetrack and ballast screening arrangement 28 is arranged to receiveballast from chain 18. Track lifting device 13 is arranged on firstmachine frame part 2 adjacent transverse ballast excavating chainsection 36 and undercarriage 12 leads the track lifting device in theoperating direction of the machine. The longitudinal displacement ofthird undercarriage 12 enables the spacing between the thirdundercarriage and track lifting device 13 to be varied.

In the illustrated embodiment, third undercarriage 12 comprises twoswivel trucks 16 and carrier plate 15 connecting the swivel trucks.Undercarriage 12 has a pivot pin whereby the undercarriage is rotatableabout vertical axis 17, and drive 14 is arranged for longitudinallydisplacing the third undercarriage between a first position (shown inchain-dotted lines in FIG. 1) for moving machine 1 between operatingsites, wherein vertical axes 6 and 17 are coaxial and vertical rotatingaxis 17 of the third undercarriage extends below vertical pivoting axis6 of machine frame parts 2 and 3, and a second position (shown in fulllines in FIG. 1) for operating machine 1 at respective operating sites,wherein vertical rotating axis 17 of third undercarriage 12 leadsvertical pivoting axis 6 of machine frame parts 2 and 3 in the operatingdirection of the machine. This positioning of the third undercarriageduring operation of the machine has the particular advantage of enablingthe pivotal link of the machine parts to be displaced from the center ofthe track towards the curvature of the track even in sharp curves. Thislateral displacement of the first machine frame part towards the outerrail, i.e. in the direction of the track curvature, enables the ballastexcavating chain to be displaced even further in that same direction sothat the track may be subtended even in sharp curves within the lateralboundaries of the track despite the wide spacing between theundercarriages.

An operator's cab holding central control panel 19 for an operator ofthe ballast cleaning machine is mounted on first machine frame part 2within range of endless ballast excavating chain 18. Ballast screeningarrangement 28 consisting of two successive ballast screens 21 isarranged to receive excavated ballast from chain 18, conveyor bandarrangement 20 conveying the excavated ballast from an output of theendless ballast excavating chain to a respective ballast screen. Asshown in the drawing, third undercarriage 12 is arranged at a rear endof machine frame part 3, in the operating direction of the machine, andballast screening arrangement 28 is mounted on this leading machineframe part. By using this machine frame part as a ballast screening car,first machine frame part 2 is relieved of carrying the heavy weight ofthe ballast screens and the track lift may be effected without problems.Arranging the third undercarriage on machine frame part 3 provides astable support for this heavily loaded machine frame part in eachposition of this displaceable undercarriage.

Cleaned ballast distributing conveyor band arrangement 22 is mounted onthe underside of first machine frame part 2 for conveying the cleanedballast from a respective ballast cleaning screen 21 to respectivedischarge points 23 and 24 behind the ballast excavating chain todistribute the cleaned ballast in the excavated ballast bed. Ballastcompacting beam 25 is arranged at first discharge point 23 to compactthe discharged cleaned ballast, the ballast compacting means beingsupported on machine frame part 2 for pivoting about an axis extendingtransversely to the longitudinal extension of this machine frame part.Vertically adjustable auxiliary track gripping clamp 27 is mounted onmachine frame part 2 immediately ahead of endless ballast excavatingchain 18, in the operating direction of the machine, the track grippingclamp comprising a pair of cooperating lifting plates pivotal intoengagement with a respective rail 10 by subtending the rail head.Trailing machine frame part 4 carries not only second discharge point 24comprising a transversely extending chute for depositing cleaned ballastin the cribs but also central power plant 29 for providing power to theoperating drives of machine 1.

FIG. 2 shows lateral boundaries 30 of the track in chain-dotted lines.For proper operation of the machine along a track section, no structuralcomponent of the machine must project beyond these boundary lines. Asshown in the drawing, all three machine frame parts 2, 3, 4 and endlessballast excavating chain 18, which surrounds track 31, are within theindicated lateral boundaries. Longitudinally displaceable thirdundercarriage 12 has been displaced into its forward position, whichcauses the rear end of leading machine frame part 3 to be movedlaterally outwardly in the illustrated track curve in the direction ofthe curvature while pivotal link 7 between machine frame parts 2 and 3is moved from its central position between rails 10 in the samedirection. This has the advantage that elongated machine frame part 2,which forms a chord in the track curve, is also laterally displaced inthis direction, which enables endless ballast excavating chain 18 to beextended in this direction for properly encompassing track 31 whilemachine frame part 2 and chain 18 remain with lateral boundaries 30.When machine 1 is moved between operating sites, longitudinallydisplaceable third undercarriage 12 is in its rear position indicated inchain-dotted lines and pivotal link 7 between machine frame parts 2 and3 is centered between the rails in the position indicated by referencenumeral 32. In this position, the vertical axis of pivot pin 17 ofundercarriage 12 is coaxial with vertical axis 6 of pivotal link 7.Chain-dotted lines 33 and 34 indicate the positions of machine frameparts 3 and 2 when the machine is moved between operating sites.

As is also shown in FIG. 2, endless ballast conveying chain 18 comprisestwo longitudinally extending, upwardly inclined sections 35 linked totransverse section 36 which extends below track 31 for excavating theballast and conveying the excavated ballast upwardly to an output of thechain whence it is conveyed by conveyor band arrangement 20 to ballastscreening arrangement 28. Transverse chain section 36 consists of twoparts 37 and 38 whose adjoining ends are linked to each other forpivoting about a vertical axis whereby longitudinally extending chainsections 35 may be pivoted into a position closely adjacent respectivesides of machine frame part 2 whereon the chain is mounted. Thus, whenthe machine is moved between operating sides, chain 18 may be collapsedwithout dismantling the same into the position shown in chain-dottedlines in FIG. 1, wherein the longitudinall extending chain sections hugthe sides of machine frame part 2 and are within lateral boundaries 30.A theoretical operating position of endless ballast excavating chain 18is indicated in dotted lines to show that the extended chain wouldproject beyond lateral boundaries 30 of the track if first machine framepart 2 were not displaced laterally outwardly into the operatingposition shown in full lines but were in the position indicated bychain-dotted lines 34, which is the position assumed when the machine ismoved between operating sites, i.e. when longitudinally displaceableundercarriage 12 is in its rear position.

As shown in FIGS. 3 and 4, machine frame part 3 is comprised of twocarrier beams 41, 42 extending parallel to each other and interconnectedby bottom plate 40. Each carrier beam defines a guide track of U-shapedcross section forming longitudinally extending guide 43 glidinglyreceiving the two side edges of support plate 44 connected tolongitudinal displacement drive 14. Carrier plate 15, which connects thetwo swivel trucks 16 of undercarriage 12, extends below support plate 44and pivot pin 17 mounts the carrier plate rotatably about a verticalaxis on the support plate. Each swivel truck 16 is rotatably mounted oncarrier plate 15 by pivot pin 45 for rotation about a vertical axis.Such a four-axle undercarriage provides a very stable support for a veryheavy load while, on the other hand, enabling the undercarriage to belongitudinally displaced without any problems. The U-shaped guide tracksprovide a solid gliding support for the support plate of theundercarriage on the machine frame part in every longitudinal positionof the undercarriage.

It is advantageous for the longitudinal displacement path ofundercarriage 12 to correspond to the spacing between pivot pins 45 ofswivel trucks 16 so that a stable support is provided for the very heavymachine frame part 3 in track curves even in the outermost end positionsof the longitudinally displaceable undercarriage.

As best shown in FIG. 4, carrier plate 15 for swivel trucks 16 is freelyrotatable on support plate 44 by pivot pin 17 so that the two swiveltrucks may readily follow the path of rails 10, regardless of thelongitudinal orientation of machine frame part 3. Pivotal link 7coupling machine frame parts 2 and 3 is a pivot pin 46 projectingdownwardly from frame part 2 and extending through bottom plate 40 offrame part 3. Gliding bearing 47 is interposed between frame part 2 andbottom plate 40.

Ballast cleaning machine 1 may be operated in the following manner:

The machine is moved on the track to an operating site while theoperator at control panel 19 supplies power from power plant 29 to drive14 to hold undercarriage 12 in its rearmost end position shown inchain-dotted lines in FIG. 1. During this movement of the machine,endless ballast excavating chain 18 is in its raised and collapsedposition shown in chain-dotted lines in FIGS. 1 and 2, whereinlongitudinally extending chain sections 35 are close to the sides offirst machine frame part 2. Pivoting axis 6 is centered between rails 10during this movement since pivot pin 17 of undercarriage 12 is coaxialwith the pivoting axis. The length of machine frame part 2, i.e. thedistance between pivot links 7 and 8 respectively coupling the oppositeends of this machine frame part to leading machine frame part 3 andtrailing machine frame part 4, is such that the machine frame part endswill not project beyond lateral boundaries 30 of the track even in thesharpest track curves.

After the operating site has been reached, drive 14 is actuated by theoperator to displace the same longitudinally into its foremost endposition shown in full lines in FIG. 1, which is its position during theoperation of the machine. The two rails 10 are cut in the plane oftransverse chain section 36 and the track section ahead of the cuttingplane in the operating direction of the machine is raised by auxiliarytrack gripping clamps 27, which are pivoted into engagement with rails10 and lifted. While the ballast under this raised track section isremoved, a pivoting drive interconnecting the two transverse chainsection parts 37, 38 is actuated to pivot the two transverse chainsection parts until the ends of longitudinal chain sections 35 linked tothe transverse chain section parts are spaced apart a distance a littlegreater than the length of ties 11. The spread transverse chain sectionis then lowered into the space below the track from which the ballasthas been removed, suitable drives linking chain 18 to machine frame part2 to enable the endless ballast excavating chain to be verticallyadjusted in a well known manner. The raised track section is thenlowered again by operation of track gripping clamps 27 and the trackrails are reconnected. The reconnected rails are then gripped by tracklifting device 13 and the track is slightly raised for continuousoperation of the machine as it advances along the track in the operatingdirection indicated by arrow 26, i.e. endless ballast excavating chain18 is rotated to excavate ballast and convey it to conveyor bandarrangement 20 for conveyance to screening arrangement 28 whence thecleaned ballast is redistributed by cleaned ballast conveyor bandarrangement 22. All of these structures and their operation are wellknown in ballast cleaning machines.

The spacing between pivot pin 17 of longitudinally displaceableundercarriage 12 and pivoting axis 6 causes first machine frame part 2to be laterally outwardly displaced in the direction of the curvature,particularly in sharp track curves. This enables endless ballastexcavating chain also to be displaced in the same direction so thattrack 31, which is eccentrically positioned with respect to machineframe part 2, may still be encircled by endless chain 18. Longitudinaladjustment of undercarriage 12 between its two end positions intointermediate positions enables the position of machine frame part 2 andendless chain 18 to be adapted advantageously to prevailing operatingconditions.

If desired, rear undercarriage 9 may be longitudinally displaceable inthe same manner as front undercarriage 12 or, alternatively, only rearundercarriage 9 may be longitudinally displaceable, i.e. at least one ofthe undercarriages arranged on one of the machine frame parts in therange of the vertical pivoting axis pivotally linking adjoining machineframe part ends is longitudinally displaceable.

What is claimed is:
 1. A ballast cleaning machine for excavating ballastfrom underneath a track and for receiving, cleaning and transporting theexcavated ballast, which comprises(a) a machine frame comprising twoframe parts, each machine frame part having opposite ends,(1) one of theends of one machine frame part adjoining one of the ends of the othermachine frame part while the machine frame part ends opposite to the oneends are remote from each other, and (2) the adjoining machine framepart ends being pivotally linked to each other for pivoting about avertical axis, (b) respective undercarriages supporting the machineframe on the track,(1) two of the undercarriages being arranged at theremote machine part ends and (2) a third one of the undercarriages beingarranged on one of the machine frame parts in the range of the verticalpivoting axis, (c) an endless ballast excavating chain arranged on afirst one of the machine frame parts, the chain including(1) atransverse section extending for operation under the track, (d) aballast screening arrangement arranged to receive excavated ballast fromthe chain, (e) a track lifting device arranged on the first machineframe part adjacent the transverse ballast excavating chain section, and(f) a drive connecting the third undercarriage to the one machine framepart whereon it is arranged for longitudinally displacing the thirdundercarriage along the track whereby the spacing between the thirdundercarriage and the track lifting device may be varied.
 2. The ballastcleaning machine of claim 1, wherein the endless ballast excavatingchain comprises two longitudinally extending sections linked to thetransverse chain section, the transverse chain section consisting of twoparts pivotally linked to each other for pivoting about a verticalcenter axis whereby the longitudinally extending chain sections may bepivoted into a position closely adjacent respective sides of the onemachine frame part whereon the chain is mounted.
 3. The ballast cleaningmachine of claim 1, wherein the one machine frame part pivotally linkedto the first machine frame part has the third undercarriage arranged ata rear end of the one machine frame part, in an operating direction ofthe machine, and the ballast screening arrangement is mounted on the onemachine frame part.
 4. A ballast cleaning machine for excavating ballastfrom underneath a track and for receiving, cleaning and transporting theexcavated ballast, which comprises(a) a machine frame comprising twoframe parts, each machine frame part having opposite ends,(1) one of theends of one machine frame part adjoining one of the ends of the othermachine frame part while the machine frame part ends opposite to the oneends are remote from each other, and (2) the adjoining machine framepart ends being pivotally linked to each other for pivoting about avertical axis, (b) respective undercarriages supporting the machineframe on the track,(1) two of the undercarriages being arranged at theremote machine part ends and (2) a third one of the undercarriages beingarranged on one of the machine frame parts in the range of the verticalpivoting axis, the third undercarriage comprising two swivel trucks anda carrier plate connecting the swivel trucks, (c) an endless ballastexcavating chain arranged on a first one of the machine frame parts, thechain including(1) a transverse section extendig for operation under thetrack, (d) a ballast screening arrangement arranged to receive excavatedballast from the chain, (e) a track lifting device arranged on the firstmachine frame part adjacent the transverse ballast excavating chainsection, (f) a drive connecting the third undercarriage to the onemachine frame part whereon it is arranged for longitudinally displacingthe third undercarriage along the track whereby the spacing between thethird undercarriage and the track lifting device may be varied, (g) asupport plate connected to the drive and having two side edges, and (h)a longitudinally extending guide on the one machine frame part glidinglyreceiving the support plate side edges,(1) the carrier plate beingrotatably mounted on the support plate.
 5. The ballast cleaning machineof claim 4, wherein the longitudinally extending guide is constituted bytwo guide tracks of U-shaped cross section defined in the one machineframe part.
 6. The ballast cleaning machine of claim 4, furthercomprising respective pivot pins rotatably mounting the swivel trucks onthe carrier plate, and the third undercarriage having a longitudinaldisplacement path corresponding to the spacing between the pivot pins ofthe swivel trucks.
 7. A ballast cleaning machine for excavating ballastfrom underneath a track and for receiving, cleaning and transporting theexcavated ballast, which comprises(a) a machine frame comprising twoframe parts, each machine frame part having opposite ends,(1) one of theends of one machine frame part adjoining one of the ends of the othermachine frame part while the machine frame part ends opposite to the oneends are remote from each other, and (2) the adjoining frame part endsbeing pivotally linked to each other for pivoting about a vertical axis,(b) respective undercarriages supporting the machine frame on thetrack,(1) two of the undercarriages being arranged at the remote machinepart ends and (2) a third one of the undercarriages being arranged onone of the machine frame parts in the range of the vertical pivotingaxis and being rotatable about a vertical axis, (c) an endless ballastexcavating chain arranged on a first one of the machine frame parts, thechain including(1) a transverse section extendig for operation under thetrack, (d) a ballast screening arrangement arranged to receive excavatedballast from the chain, (e) a track lifting device arranged on the firstmachine frame part adjacent the transverse ballast excavating chainsection, and (f) a drive connecting the third undercarriage to the onemachine frame part whereon it is arranged for longitudinally displacingthe third undercarriage along the track whereby the spacing between thethird undercarriage and the track lifting device may be varied,(1) thedrive being arranged for longitudinally displacing the thirdundercarriage between a first position for moving the machine betweenoperating sides, wherein the vertical axes are coaxial and the verticalrotating axis of the third undercarriage extends below the verticalpivoting axis of the machine frame parts, and a second position foroperating the machine at respective ones of said sides, wherein thevertical rotating axis of the third undercarriage leads the verticalpivoting axis of the machine frame parts in an operating direction ofthe machine.